1. Field of the Invention
The present invention is directed to preparing materials for chrome plating and to finishing chrome plated materials, and in particular, to methods and apparatus for improving the corrosion resistance of chrome plated materials.
2. The Prior Art
Materials are chrome plated to reduce surface corrosion of the materials. Nevertheless, despite the chrome plating, surface corrosion still occurs and presents problems. This is particularly true in applications where there is intimate contact between the surface of the chrome plated materials and another material. Thus, for example, chrome plated rods used in hydraulic applications come into contact with seals made of rubber and similar materials. Surface corrosion of such rods has the additional disadvantage of causing accelerated wear of the seals. In use, such rods are subjected to high temperatures during operation of the equipment in which they are used, which increases the occurrence of corrosion.
In order to improve the corrosion resistance of chrome plated rods and the like, they are subjected in the prior art to a polishing process. A chrome plated rod is advanced along a line from an entrance end upon a series of pairs of offset rollers that both rotate and advance the rod from the entrance end to the exit end of the line. Generally, after the rod is placed on the offset conveying rollers, the periphery of the chrome plated rod is initially subjected to wet abrasive polishing at one or more polishing stations. After such wet abrasive polishing, a buffing compound, of any of a selected one of a number of commercially available mixtures, is applied to the rotating chrome plated rod. Usually such buffing compounds are applied in a multi-phase mixture by spraying them onto the rotating and advancing rod.
The prior art process then subjects the rod, with the buffing compound applied, to a series of buffing steps at a number of buffing stations. Generally, three buffing stations are used in the prior art to provide the required amount of polishing or buffing to sufficiently drive the buffing compound into the micro cracks in the chrome plated surface. Thus, open micro cracks in the chrome plated surface are sealed against corrosion by the impregnated buffing compound.
In such prior art processes, as the compound treated chrome plated surface is subjected to more polishing or buffing, it results in a higher surface finish. Thus, in the prior art process of improving the corrosion resistance of chrome plated materials, there is a corollary between the degree of surface finish and the expected resultant corrosion resistance. However, particularly in hydraulic applications, there is a disadvantage to having too high of a surface finish as it impedes the effectiveness of the cooperating seals. Nevertheless, if the corrosion resistance of the chrome plated rods is not significantly improved by an application of a buffing compound, there will be a resulting increase in downtime of production of the hydraulic equipment while the corroded rods and/or the ruined seals need to be replaced.
The effective corrosion resistance provided by the chrome plating of materials is also effected by the preparation of the materials to be chrome plated. Thus, as the chrome plated materials, such as rods, are subjected in the prior art to a polishing process after they are chrome plated, the rods are also subjected to a polishing process prior to chrome plating. A line like that used for advancing the chrome plated rod is also used for advancing the rods to be chrome plated. Accordingly, a rod to be chrome plated is advanced along a line from and entrance end upon a series of pairs of offset rollers that both rotate and advance the rod from the entrance end to the exit end of the line. Generally, after the rod is placed on the offset conveying rollers, the periphery of the rod to be chrome plated is subjected to abrasive polishing at one or more polishing stations. Usually, the material to be chrome plated is subjected to a series of abrasive polishing steps in which the abrasive or grit used to polish will vary to produce a smoother finish as the material to be chrome plated advances from the entrance end toward the chrome plating.
After the rod is abrasively polished in the prior art process, it is immersed in a caustic solution cleaning tank and generally then subsequently immersed in one or more rinse tanks before being subjected to plating. In the prior art, normally the first plating step after the rod is abrasively polished and cleaned is reverse etching, prior to the actual chrome plating of the rod.
Generally, all other things being equal, the smoother the finish of the material to be chrome plated, the better will be the corrosion resistance provided by the chrome plating. Unfortunately, the abrasive polishing of the material to be chrome plated generally leaves strands, filaments or “fine hairs” of microscopic size. Such “fine hairs” are measured in microns, and their size varies as a result of the particular belt or wheel used to abrasively polish the material to be chrome plated. The presence of such “fine hairs” when the material to be chrome plated is reverse etched results in micro cavities wherever the “fine hairs” are present, which detrimentally affects the resulting corrosion resistance provided by the chrome plating. To the extent that such micro cavities or pockets can be eliminated prior to chrome plating, the effective corrosion resistance will be improved.
Accordingly, it would be desirable to provide a method and apparatus for improving the corrosion resistance of chrome plated materials, in order to increase the life of such materials and to decrease the downtime of machines in which they are used.
These and other desirable characteristics of the present invention will become apparent in light of the present specification, including claims, and drawings.